Electrolytic reduction cell having detachably supported electrodes



Oct. l, 1968 E. w. CUMMINGS ET AL.

3,404,081 oN CELL IHAVING DETACHABLY suPPoRTED ELECTRODES 5 Sheets-Sheet l Filed Aug. 9, 1965 INVENTORS BY 964W y ATTORNEY Oct. l, 1968 E. w. CUMMINGS ET AL 3,404,081

ELECTROLYTIC REDUCTION CELL HAVING DETACHABLY SUPPORTED ELECTRODES Filed Aug. 9, 1965 5 Sheets-Sheet INVENTORS ERROL W. CUMMINBS JOHN R. PETERSON ATTQRNEY Oct. l, 1968 E w, CUMM|NG5 ET AL 3,404,081

v ELECTROLYTIC REDUCTION CELL HAVING DETACHABLY SUPPORTED ELECTRODES Filed Aug. i, 1965 5 Sheets-Sheet 5 INVENTORS ERROL VI. CUMMINGS JOHN R. PETERSQN yu, Aoaue,

Oct. l, 1968 E. w. cuMMlNGs ET AL 35404081 ELECTROLYTIC REDUCTION CELL HAVING DETACHABLY SUPPORTED ELECTRODES .filed Aug. 9, 196s i 5 sheets-sheet 4 INVENTORS ERROL W. CUMMINGS JOHN R. PETERSON Wwf ATTORNEY Oct. 1, 1968 E, W, CUMMlNGS ET AL 3,404,081

ELECTROLYTIC REDUCTION CELL HAVING DETACHABLY SUPPORTED ELECTRODES Filed Aug. 9, 1965 5 Sheets-Sheet 5 rw .f i 1 g i l: l: f li 2 f; 24 I I! 'y I 22 l! i i e e w' i i: LJ y NLE 2S g FJ g. 9

INVENTORS ERROL Vl- CUMMINGS JOHN R. PETERSQN v BY 6 0*/ v ATTORNEY United States Patent O 3,404,081 ELECTROLYTIC REDUCTION CELL HAVING DETACHABLY SUPPORTED ELECTRODES Errol W. Cummings, Moraga, and John R. Peterson, Oakland, Calif., assignors to Kaiser Aluminum & Chemical Corporation, Oakland, Calif., a corporation of Delaware Filed Aug. 9, 1965, Ser. No. 478,162 5 Claims. (Cl. 204-243) This invention relates to electrolytic cells employing electrodes supported by individual bars or rods of conductor material. More particularly, this invention concerns a novel system for suspending prebaked anodes in electrolytic cells for the reduction of aluminum-containing compounds, e.g., alumina.

In the prebaked type of electrolytic cell used in the aluminum industry, a plurality af .anodes are individually suspended from metal anode rods or conductor bars, for example of copper or aluminum, which in turn are suitably atlixed to supporting conductors or anode bus bars which are positioned horizontally Iabove the cavity of the electrolytic cell. During operation of the cell, the lower portions of the anodes are consumed or burned olf and the anodes must be lowered in order to have the lower surface thereof in the proper position in the electrolyte. Accordingly, a suitable jacking mechanism must be provided for lowering and raising the supporting conductors. In order to avoid the necessity of removing and replacing all of the anodes at once, they are staggered in their vertical position such that only one or two require replacing at a given time. In view of such staggering, it is necessary, when the supporting conductors have reached their lowest position, to be able to maintain the anodes in a xed positon relative to the electrolyte while the supporting conductors are raised to their highest position. After the supporting conductors are raised to their highest position, the anodes may be lowered further by lowering the supporting conductors. Accordingly, suitable structural members or auxiliary anodes buses are provided above the parallel to the supporting conductors. The metal anode abrs are of sufficient length such that the ends of the bars extend to a position above the structural members when the electrode is at its lowest position. Thus, when the supporting conductors reach their lowest position, the bars may be affixed to the structural members to maintain them in position. 'I'he bars may then be disengaged from the supporting conductors and the supporting conductors moved to the uppermost position. The bars may be again aixed to the supporting conductors and disengaged from the structural members. Lowering of the bars and electrodes may then be resumed by lowering the 'supporting con-ductors.

When an anode has been consumed to a point where it needs to be replaced, the replacement is done with the aid of a suitable lifting device such as a crane. To facilitate such lifting, an opening is generally provided in the upper end of the metal conductor bars for engagement by a hook of the crane. Accordingly, the metal conductor bars must be sufliciently long to extend to the structural members and Ialso extend somewhat beyond to make possible engaging the crane hook in the opening.

In addition to the rather complicated series of steps that must be gone through in order to raise or lower an anode this system has several other disadvantages. In the above outlined prior art system, the conductor bar is placed vertically against a vertical face on the anode bus bar and while held in place, pressure is applied by a horizontally acting clamp device to make an electrical contact between the conducto-1' rod and the anode bus bar. This method causes arcing of the contact surfaces when a consumed anode assembly is removed and when a new assembly is placed in position. In addition, arcing,

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occurs at the contact surfaces each time it is necessary to adjust the elevation of an anode to maintain proper current distribution. Adjustment requires slacking olf the clamp to shift the metal conductor either up or down with respect to the anode bus bar and then tightening the clamp again to remake the stationary contact.

Accordingly, the instant invention is concerned with providing a novel system wherein each anode of a cell group may be 'vertically adjusted without changing the position of or breaking the electrical connection between other anode assemblies in the cell and the anode bus bar. When replacing spent carbon anodes, the current flow from an anode assembly to the electrolyte is broken at the surface of the electrolyte on removal, thereby eliminating arcing between metal conductor rod and anode bus bar. This advantage of the novel system of the invention becomes extremely important when current ow through each anode is increased from 2,000 amperes upward.

The instant invention is also concerned with providing Ian open path for easy positioning and holding of the anode assembly on the conductor bar just prior to clamping.

Further advantageous features of the novel system of the instant invention include:

(l) Any one consumed anode can be replaced without disturbing the connection, connection devices or position of the other anodes in the cell;

(2) An auxiliary anode bus is not required as in the above-outlined prior art arrangement to hold all the anodes in a set position while the anode bus is being repositioned at the top position;

(3) The anode assembly connect-ion to the anode bus bar may be made without moving the clamping device h-orizontally or removing the clamping device altogether to allow the anode assembly to be positioned on the anode bus;

(4) The anode rod conguration results in substantially more contact surface per given length of anode rod, thereby greatly reducing the power loss across the connection. This latter advantageous feature is of considerable importance as current flow to each anode is increased from 2,000' amperes upward.

These and other purposes and advantages of the instant invention will become more apparent from a review of the ensuing detailed description taken in conjunction with the accompanying drawings.

This invention relates to an electrolytic cell comprising a lining which defines a cavity adapted to contain an electrolyte and a prebaked anode disposed within the cavity. A flexible lbus conductor is connected to an anode bus bar and positioned above the cavity in combination with an elongated electrical connection plate attached to the exible bus conductor and positioned above the cavity with the axis of the plate being substantially in a horizontal plane. Suitable slide means are positioned above the cavity and adapted to receive the extremity of the connection plate removed from the anode bus and to be slidably adjustable along a vertical plane. The prebaked anode is attached by suitable means to the lower end of a metal conductor bar, the upper portion of which is adapted to be held against the electrical connection plate in current transmitting contact. Suitable means for holding the metal conductor bar and electrical connection plate with vertical pressure in current transmitting contact are provided in the system.

The accompanying drawings are illustrative of advantageous embodiments of this invention as applied to aluminum reduction cells.

FIG. 1 is an end elevational view in cross section, with parts removed for purposes of clarity, of an aluminum reduction cell embodying the principles of this invention.

FIG. 2 is a front elevational view with parts removed for purposes of clarity of one embodiment of the suspension system of this invention.

FIG. 3 is a side elevational view with parts removed for purposes of clarity of the embodiment shown in FIG. 2.

FIG. 4 is a front elevational view with parts removed for purposes of clarity of another embodiment of the suspension system of this invention.

FIG. 5 is a side elevational View with parts removed for purposes of clarity of the embodiments shown in FIG. 4.

FIG. 6 is a front elevational view with parts removed for purposes of clarity of another embodiment of the suspension system of this invention.

FIG. 7 is a side elevational view with parts removed for purposes of clarity of the embodiment shown in FIG. 6.

FIG. 8 is a front elevational view with parts removed for purposes of clarity of another embodiment of the suspension system of this invention, and

FIG. 9 is a side elevational view with parts removed for purposes of clarity of the embodiment shown in FIG. 8.

Referring now more particularly to the drawings in which the same reference numerals have been applied to corresponding parts, and with particular reference to FIG. l, an aluminum reduction cell 10 is shown having a carbon lining 12 which defines a cavity 14 adapted to contain a molten aluminum pad 13 and an electrolyte 17 consisting essentially of alumina dissolved in cryolite. Carbon lining 12 is supported by a shell 11 of suitable material, such as steel, a layer of insulation 1S being provided between lining 12 and shell 11. Within the shell 11 are disposed a plurality of prebaked carbon anodes 16 suspended in the electrolyte by means of metal conductor bars 18 by a suitable means. One such means is illustrated in FIG. l wherein anodes 16 are provided with mild steel stubs 19 embedded therein and metal conductor bars 18 are affixed to stubs 19 by bolts 20 and nuts 21.

Other means for aiiixing bars 18 to anodes 16 may, of course, be used. For example, a recess may be provided in the upper portion of anode 16 substantially larger than the cross section of the conductor bars 18. The lower ends of bars 18 are placed in the recess and molten cast iron is poured into the recess around conductor bars 18 and allowed to solidify.

Current is delivered to the cell 10 by a suitable anode bus bar 22 through exible bus conductors 23 and elongated electrical connection plates 24. Anode bus bars 22 are fabricated from a suitable metal having high electrical conductivity, e.g., aluminum, as are flexible bus conductors 23 and elongated electrical connection plates 24. From the anodes 16 the current passes through the elec trolyte 17 and molten aluminum pad 13 to lining 12 and out through collector bars 25 embedded in lining 12, exible conductors 42 and cathode bus conductor 43. Suitable slide means 26 are positioned above cavity 14 and are adapted to receive the extremity of connection plate 24 removed from the anode bus 22 and are slidably adjustable along a vertical plane. The slide means are moved by mechanical jacks 27 connected to a suitable source of power 28 such as an air motor. If desired, dust covers 29 may be provided over the screw threads of jacks 27 to protect them from alumina dust.

The upper portion of metal conductor bar 18 is adapted to be held against electrical connection plate 24 in current transmitting contact by suitable means such as clamp 30 providing vertical pressure. In many instances, utilization of a clamp as the holding means to provide vertical pressure will not be necessary as the weight of the metal conductor bar 18 and anode 16 assembly will provide sucient vertical pressure for current transmitting contact between the metal conductor bar 18 and the electrical connection plate 24 to be made. Thus, in this instance, the weight of the metal conductor bar 18 and anode 16 assembly would itself constitute the holding means. It should be noted that although metal conductor bar 18 is shown twisted in FIG. l to provide a greater area of metal to be held against electrical connection plate 24 in current transmitting contact with vertical pressure, this is not absolutely necessary. The conductor bar 18 may be designed as shown hereinafter to have sullicient thickness so as not to necessitate twisting in order to provide sufcient current transmitting contact area.

The suspension system may be seen with greater clarity in FIGS. 2-9 inclusive wherein the same reference numerals have been applied to corresponding parts.

With reference now to FIGS. 2 and 3 wherein one embodiment of the suspension system is shown, it may be seen that slide means 26 comprises a slide plate 31 slidably adjustable along a vertical plane and parallel guide rails 32. The guide rails 32 are attached to the superstructure of the reduction cell (not shown) by suitable means such as Welding. The guide rails 32 may be formed, for example, from structural steel I beams. Each vertical side of slide plate 31 moves within the channel formed by the web and leg members of an I beam. Plate 31 is attached to the bottom of jack 27 mounted on beam 44 by suitable means such as clevis and pin assembly 33.

In the embodiment shown in FIGS. 2 and 3, the end of electrical connection plate 24 removed from the anode bus 22 is provided with or split into two horizontally extending legs 34 adapted to be received by plate 31 of slide means 26. Leg supports 35 are attached to plate 31 to support legs 34 in a horizontal direction. The upper portion of metal conductor bar 18 is T-shaped and adapted to be held with an arm 36 of the T against each leg 34 of the electrical connection plate with vertical pressure in current transmitting contact.

FIGS. 4 and 5 wherein the same reference numerals have been applied to corresponding parts, show another embodiment of the suspension system of this invention. In this embodiment, the end of the electrical connection plate 24 removed from the anode bus 22 is provided with or split into two downwardly converging legs 34 adapted to be received by and supported by slide means 26, specifically by leg supports 35 mounted on plate 31. If desired, leg supports 35 may be pivotally mounted on plate 31 by means of pivot pins 38. The upper portion of conductor bar 18 is shaped in the form of a wedge 37 and is adapted to be held against and within downwardly converging legs 34 of the electrical connection plate 24 with vertical pressure in current transmitting contact. Although frequently the weight of the anode 16-conductor bar 18 assembly would provide suicient vertical pressure to insure current transmitting contact, clamp 30 may be used as a supplementary holding means operating through wedge shaped pressure plate 39 to provide additional vertical pressure. If a solid rather than an open wedge were used, then a at pressure plate would be used.

FIGS. 6 and 7 wherein the same reference numerals have been applied to corresponding parts, show another embodiment of the suspension system of this invention. In this embodiment, the upper portion of conductor bar 18 is hook shaped with the hook 40 opening horizontally. The free end of hook 40 is adapted to be held against electrical connection plate 24 with vertical pressure in current transmitting contact. As shown, hook 40 may be flared to provide additional contact area. Although often the weight of the anode 16 and conductor bar 18 will be sufcient to hold the free end of hook 40 against electrical connection plate 24 with vertical pressure in current transmitting contact, this holding means may be supplemented by clamp 30 acting through horizontal pressure plate 39 thereby providing additional vertical pressure.

FIGS. 8 and 9 wherein the same reference numerals have been applied to corresponding parts, show a still further embodiment of the suspension system of this invention. In this embodiment the end of electrical connection plate 24 removed from the anode bus 22 is provided with or split into two downwardly extending legs 34 adapted to be received by and pivotally attached to plate 31 of slide means 26. As shown, this may be done through leg supports 35 pivotally attached to plate 31 by pivot assembly 41. In this embodiment the upper portion of conductor bar 18 may be of the same shape as the rest of the bar. In this way, bar 18 is adapted to be held against and within downwardly extending legs 34 of the electrical connection plate 24 in current transmitting contact as the legs 34 pivot downwardly under the vertical pressure of the conductor bar 18. If desired, clamp 30 acting through pressure plate 39 may be used to provide supplemental vertical pressure thereby insuring good current transmitting contact between conductor bar 18 and connection plate legs 34.

It can be seen that the novel suspension system of this invention permits the vertical adjustment of each anode in a cell without having to change the position of other anodes in the cell. Similarly, it is not necessary to break the electrical connection between other anode assemblies and the bus bar when adjusting one anode. Further, the novel suspension systems of this invention permit breaking the current flow from each anode assembly to the electrolyte when changing anodes. This is done by raising the anode assembly until the anode is above the surface of the electrolyte, thus breaking the electrical circuit. This eliminates arcing between the metal conductor rod and electrical connection plate when replacing spent anode carbons. The elimination of the arcing means that there is little attack to the contact surfaces of the conductor rod and electrical connection plate. Thus, their life is greatly extended and current drop across the connection is kept to a minimum. This feature becomes extremely important when current flow through each anode of a cell is increased from 2,000 amperes upwards.

The novel suspension systems of this invention allow the replacement of any individual spent vanode without disturbing the connection devices or position of other anodes in the cell. An auxiliary anode bus or portable auxiliary anode are not required, as in the prior art arrangements, to hold all the anodes while the anode bus is being repositioned to the top position. The novel suspension systems of this invention permit current transmitting contact to be obtained between the metal conductor bar and electrical connection plate with vertical pressure instead of horizontal pressure through a horizontally acting clamp as in the prior art. Since much of the vertical pressure to create the desired current transmitting contact is due to the weight of the conductor bar-anode assembly, only relatively little clamping pressure, if any, is needed. This means that distortion of the conductor bar due to clamping pressure is minimized and the useful life of the conductor bar is greatly extended.

While there have been shown and described herein above the presently preferred embodiments of this invention, it is to be understood that the invention is not limited thereto and that various changes, alterations, and modifications can be made thereto without departing from the spirit and scope thereof as dened in the appended claims.

What is claimed is:

1. An electrolytic reduction cell comprising:

(a) a lining which defines a cavity adapted to contain an electrolyte;

(b) a prebaked anode disposed within the cavity;

(c) a exible bus conductor connected to an anode bus bar and positioned above the cavity in combination with (d) an elongated electrical connection plate attached to the llexible bus conductor and positioned above the cavity, with the axis of the plate being substantially in a horizontal plane;

(e) slide means positioned above the cavity and adapted to receive the extremity of the connection plate removed from the anode bus and to be slidably adjustable along a vertical plane;

(f) a metal conductor bar, the upper portion of which is adapted to be held against the electrical connection plate in current transmitting contact;

(g) means for holding the metal conductor bar and electrical connection plate with vertical pressure in current transmitting contact;

(h) means for attaching the prebaked anode to the lower end of the metal conductor bar.

2. The electrolytic reduction cell of claim 1 wherein the end of the electrical connection plate removed from the anode bus is provided with two horizontally extending legs adapted to be received by the slide means and the upper portion of the conductor bar is T-shaped and adapted to be held with an arm of the T against each leg of the electrical connection plate with vertical pressure in current transmitting contact.

3. The electrolytic reduction cell of claim 1 wherein the end of the electrical connection plate removed from the anode bus is provided with two downwardly converging legs adapted to be received by the slide means and the upper portion of the conductor bar is wedge shaped and adapted to be held against and Within the downwardly converging legs of the electrical connection plate with vertical pressure in current transmitting contact.

4. The electrolytic reduction cell of claim 1 wherein the upper portion of the conductor bar is hook shaped with the hook opening horizontally and the free end of the hook is adapted to be held against the electrical connection plate with vertical pressure in current transmitting contact.

5. The electrolytic reduction cell of claim 1 wherein the end of the electrical connection plate removed from the anode bus is provided with two downwardly extending legs adapted to be received by and pivotally attached to the slide means and the upper portion of the conductor bar is adapted to be held against and within the downwardly extending legs of the electrical connection plate in current transmitting contact as they pivot downward under the vertical pressure of the conductor bar.

References Cited UNITED STATES PATENTS 3,245,898 4/ 1966 Wunderli 204-243 XR FOREIGN PATENTS 922,290 3/ 1963 Great Britain.

JOHN H. MACK, Primary Examiner.

D. R. VALENTINE, Assistant Examiner. 

1. AN ELECTROLYTIC REDUCTION CELL COMPRISING: (A) A LINING WHICH DEFINES A CAVITY ADAPTED TO CONTAIN AN ELECTROLYTE; (B) A PREBAKED ANODE DISPOSED WITHIN THE CAVITY (C) A FLEXIBLE BUS CONDUCTOR CONNECTED TO AN ANODE BUS BAR AND POSITIONED ABOVE THE CAVITY IN COMBINATION WITH (D) AN ELONGATED ELECTRICAL CONNECTION PLATE ATTACHED TO THE FLEXIBLE BUS CONDUCTOR AND POSITIONED ABOVE THE CAVITY, WITH THE AXIS OF THE PLATE BEING SUBSTANTIALLY IN A HORIZONTAL PLANE; (E) SLIDE MEANS POSITIONED ABOVE THE CAVITY AND ADAPTED TO RECEIVE THE EXTREMITY OF THE CONNECTION PLATE REMOVED FROM THE ANODE BUS AND BE SLIDABLY ADJUSTABLE ALONG A VERTICAL PLANE; (F) A METAL CONDUCTOR BAR, THE UPPER PORTION OF WHICH IS ADAPTED TO BE HELD AGAINST THE ELECTRICAL CONNECTION PLATE IN CURRENT TRANSMITTING CONTACT; (G) MEANS FOR HOLDING THE METAL CONDUCTOR BAR AND ELECTRICAL CONNECTION PLATE WITH VERTICAL PRESSURE IN CURRENT TRANSMITTING CONTACT; (H) MEANS FOR ATTACHING THE PREBAKED ANODE TO THE LOWER END OF THE METAL CONDUCTOR BAR. 